Diversity and Seasonal Succession of the Phytoplankton Community in Doi Tao Lake, Chiang Mai Province, Northern Thailand

Abstract

The diversity and seasonal succession of phytoplankton were studied in Doi Tao lake, Chiang Mai, Thailand during September 2003 through to August 2004. The phytoplankton communities consisted of 162 species in 98 genera of 6 divisions. The number of species and density of phytoplankton showed high seasonal variation with high species number and density of phytoplankton in winter and summer, but low in the rainy season. Cyanophytes had the highest density during the winter and summer with three dominant species viz.: Cylindrospermopsis philippinesis, Lyngbya limnetica and Oscillatoria sp. Chrysophytes contributed the highest phytoplankton density in the rainy season with a dominant species, Aulacosiera granulata. Phytoplankton communities had the highest and lowest Shannon-Weaver diversity indices in the winter and summer, respectively. The highest Evenness index occurred in both the winter and rainy seasons, whereas the minimum was in winter. Sequential seasonal phytoplankton succession in Doi Tao lake was divisions Cyanophyta followed by Chrysophyta.